SignalUtils::IirFilter Function

SignalUtils Namespace

Overload List

#SignatureDescription
1void IirFilter(TVec *Src, TVec *Dst, TIirState &IIRState);Filter data with an IIR filter.
2void IirFilter(TVec *Data, TIirState &IIRState, bool LinearPhase = false);Filter data with an IIR filter.
3void IirFilter(TVec *Data, TVec *Num, TVec *Den, bool LinearPhase = false);Filter Data and place the result back in Data.
4void IirFilter(double Src, double &Dst, TIirState &IIRState);Filter data with an IIR filter.
5void IirFilter(float Src, float &Dst, TIirState &IIRState);
6void IirFilter(const TCplx &Src, TCplx &Dst, TIirState &IIRState);Filter data with an IIR filter.
7void IirFilter(const TSCplx &Src, TSCplx &Dst, TIirState &IIRState);

Overload 1: void IirFilter(TVec *Src, TVec *Dst, TIirState &IIRState);

Filter data with an IIR filter.

#NameTypeDescription
1SrcTVec *
2DstTVec *
3IIRStateTIirState &
Remarks:

Filter data in Src and place the result in Dst. IirState must be initialized with a call to IirInit.

Note
Use this routine for filtering of streaming data.

Examples
#include "MtxExpr.h"
#include "Units.IIrFilters.h"
#include "Units.SignalUtils.h"

using namespace Dew;
using namespace Dew::Math;
using namespace Dew::Signal;
using namespace Dew::Signal::Units::IIRFilters;
using namespace Dew::Signal::Units::SignalUtils;

void Example()
{
    Vector b, c, Response, Response1, num, den;
    TIirState State;
    int n, i;

    Tone(b, 300, 6.0/300, 0, 1);

    //   Alternative: try gaussian noise
    //    b = RandGauss(300, TMtxFloatPrecision::mvDouble);

    c.Size(b);
    ChebyshevIFilter(6, 0.2, DewArray<double>{0.6}, TFilterType::ftLowpass, false, num, den);
    State = TIirState();
    IirInit(num, den, State);
    //Alternative 1, IIR streaming
    n = 10;
    int bLength = b.Length;
    for (i = 0; i <= (bLength / n) - 1; i++)
    {
        b.SetSubRange(i*n, n);
        c.SetSubRange(i*n, n);
        IirFilter(b, c, State);
    }

    //Alternative 2 single block filter (does not require TIirState)
    //                c.Copy(b);
    //                IirFilter(c, num, den, true);

    //Alternative 3 single block
    //                c.Copy(b);
    //                IirFilter(c, State);

    c.SetFullRange();
    b.SetFullRange();
    FrequencyResponse(b, nullptr, Response, 8, true, TSignalWindowType::wtHanning);
    FrequencyResponse(c, nullptr, Response1, 8, true, TSignalWindowType::wtHanning);
    IirFree(State);
}
Declared in Dew::Signal::Units::SignalUtils · Dew.Signal/Units.SignalUtils.h · Cross-compiler

Overload 2: void IirFilter(TVec *Data, TIirState &IIRState, bool LinearPhase = false);

Filter data with an IIR filter.

#NameTypeDescription
1DataTVec *
2IIRStateTIirState &
3LinearPhase = falsebool
Remarks:

Filter Data and place the result back in Data. Use this routine for filtering of non-consecutive blocks of data. Set LinearPhase to True to double filter attenuation and ensure no phase distortion and no phase delay.

Declared in Dew::Signal::Units::SignalUtils · Dew.Signal/Units.SignalUtils.h · Cross-compiler

Overload 3: void IirFilter(TVec *Data, TVec *Num, TVec *Den, bool LinearPhase = false);

Filter Data and place the result back in Data.

#NameTypeDescription
1DataTVec *
2NumTVec *
3DenTVec *
4LinearPhase = falsebool
Remarks:

The Iir filter is defined with a transfer function. Num is numerator and Den is denominator. Set LinearPhase to True to double filter attenuation and ensure no phase distortion and no phase delay (except for the initial transition regions).

Examples
#include "MtxExpr.h"
#include "Units.IIrFilters.h"
#include "Units.SignalUtils.h"

using namespace Dew;
using namespace Dew::Math;
using namespace Dew::Signal;
using namespace Dew::Signal::Units::IIRFilters;
using namespace Dew::Signal::Units::SignalUtils;

void Example()
{
    Vector b(0);
    Vector c(0);
    Vector num(0);
    Vector den(0);
    Vector Response1(0);
    Vector Response2(0);
    TIirState state;
    int n;
    int i;

    Tone(b, 300, 6.0/300, 0, 1, false);

    //   Alternative: try gaussian noise
    //    b = RandGauss(300, TMtxFloatPrecision::mvDouble);

    c.Size(b);
    ChebyshevIFilter(6, 0.2, DewArray<double>{0.6}, TFilterType::ftLowpass, false, num, den, TIirFrequencyTransform::ftStateSpaceAnalog);
    IirInit(num, den, state, false);
    //Alternative 1, IIR streaming
    n = 10;
    int bLength = b.Length; //to prevente reevaluaton inside "for"
    for (i = 0; i < (bLength/n); i++)
    {
        b.SetSubRange(i*n, n);
        c.SetSubRange(i*n, n);
        IirFilter(b, c, state);
    }
    IirFree(state);

    //Alternative 2 single block filter (does not require TIirState)
    //                c.Copy(b);
    //                IirFilter(c, num, den, true);

    //Alternative 3 single block
    //                c.Copy(b);
    //                IirFilter(c, state);

    c.SetFullRange();
    b.SetFullRange();
    FrequencyResponse(c, nullptr, Response1, 1, true, TSignalWindowType::wtHanning, 0);
    FrequencyResponse(b, nullptr, Response2, 1, true, TSignalWindowType::wtHanning, 0);
}
See Also: SignalUtils::SavGolayFilter, OptimalFir::RemezImpulse, SignalUtils::FirInit, SignalUtils::IirInit, SignalUtils::IirFree
Declared in Dew::Signal::Units::SignalUtils · Dew.Signal/Units.SignalUtils.h · Cross-compiler

Overload 4: void IirFilter(double Src, double &Dst, TIirState &IIRState);

Filter data with an IIR filter.

#NameTypeDescription
1Srcdouble
2Dstdouble &
3IIRStateTIirState &
Remarks:

Filters sample Src and places real valued output of the filter in Dst.

Declared in Dew::Signal::Units::SignalUtils · Dew.Signal/Units.SignalUtils.h · Cross-compiler

Overload 5: void IirFilter(float Src, float &Dst, TIirState &IIRState);

#NameTypeDescription
1Srcfloat
2Dstfloat &
3IIRStateTIirState &
Declared in Dew::Signal::Units::SignalUtils · Dew.Signal/Units.SignalUtils.h · Cross-compiler

Overload 6: void IirFilter(const TCplx &Src, TCplx &Dst, TIirState &IIRState);

Filter data with an IIR filter.

#NameTypeDescription
1Srcconst TCplx &
2DstTCplx &
3IIRStateTIirState &
Remarks:

Filters sample Src and places complex output of the filter in Dst.

Declared in Dew::Signal::Units::SignalUtils · Dew.Signal/Units.SignalUtils.h · Cross-compiler

Overload 7: void IirFilter(const TSCplx &Src, TSCplx &Dst, TIirState &IIRState);

#NameTypeDescription
1Srcconst TSCplx &
2DstTSCplx &
3IIRStateTIirState &
Declared in Dew::Signal::Units::SignalUtils · Dew.Signal/Units.SignalUtils.h · Cross-compiler